As a flat panel display apparatus, TFT-LCDs (Thin Film Transistor Liquid Crystal Display) have been applied in the field of high performance display more and more due to their features such as small volume, low power consumption, no irradiation and relatively low manufacturing costs.
A TFT-LCD is comprised of an array substrate and a color filter substrate with a liquid crystal layer disposed therebetween. In addition, a first polaroid is disposed on the top surface of the color filter substrate and a second polaroid is disposed between the array substrate and the backlight unit. The above-mentioned polaroids (first polaroid and second polaroid) are made of polyvinyl alcohol (PVA) film and can only transmit one polarized component of the natural light while absorb the other polarized component. In this way, large amount of light will be lost, which will lower the light utilization ratio greatly.
A TFT-LCD may also have a wire grating polaroid made of metal material. When light irradiates the wire grating polaroid, under the action of oscillation of free electrons on the metal surface, light vibrating parallel to the electric vector component of the wire grating is almost all reflected, while light perpendicular to the electric vector component of the wire grating is almost all transmitted.
However, since the above-mentioned wire grating polaroid is made of metal material, reflectivity for light on the metal material surface is very high. When external light is strong, light can transmit a screen of a display device and hit the wire grating polaroid. While the wire grating polaroid would reflect light back, even into human eyes, which would interfere with a user in viewing images on the display screen and impact viewing effect for the user.